well i will go with Gtalk only.Yahoo is not good with the call features.Their voice transfers are poor.As far US is concerned Yahoo mess experiencing lot of problems.Thats the main reason why US ppl using Skype and Gtalk alone

i am using yahoo messenger, rediffbol, gtalk & skype but i almost like to use yahoo messenger because yahoo messenger have talkies,smiles & good interesting audibles other messengers not having these type of features. so i like yahoo messenger.